We are exploring hematopoietic stem cell reconstitution with cryopreserved autologous stem cells (from marrow or peripheral blood) as a means of promoting prompt hematopoietic recovery following the administration of intensive anti-tumor therapy. Patients studied have neoplasms resistant to conventional dose therapy or are receiving adjuvant treatment. Methods for amplification of peripheral blood stem cell pools are being studied (in man and the dog) in an attempt to provide adequate numbers of such cells from a single 4 hour continuous flow centrifugation. The effect of therapeutic irradiation on the availability of pools of peripheral blood stem cells is being assessed. Cyclic neutropenia in man is being used as a model for hematopoietic regeneration, and gallium scanning following granulocyte transfusion is being studied as a means of diagnosing occult infection in neutropenic patients. Clinical trials to define which cancer patients require HLA-matched platelet transfusions (vs. unmatched) are underway. Finally, the potential of the continuous flow centrifuge as a therapeutic tool (e.g., to remove insulin antibodies) is under study.